The AVC (Automatic Voltage Control) master system running in the control center controls the reactive resources in the power system, and plays an important role in ensuring the security, high-quality and economical operation of the power system. The typical AVC master system includes the reactive optimization for the whole power system in the hour level and the subregion control decision in the minute level. In particle, according to the reactive optimization for the whole power system, the preset optimal voltages of the key buses can be obtained to provide the control objectives for the subregion control decision; and according to the subregion control decision, the adjustments of the reactive means can be adjusted to ensure each key bus to track the preset optimal voltages.
In the subregion control decision, the conventional AVC master system ensures the voltages of the key buses (specified artificially, hereinafter referred to as the central buses) of the power system to meet the optimized preset voltages. However, if the electrical contact between the two power plants is close (i.e. strong coupling), it is possible to make the unreasonable distribution of the two strong coupling power plants due to the requirements for the voltages, thus affecting the security and economical operation of the power system.